Yale researchers using a new brain imaging analysis
method have confirmed that smoking cigarettes
activates a dopamine-driven pleasure and
satisfaction response differently in men compared to
women.
The study, published in The Journal of Neuroscience,
used a new way of analyzing PET (positron emission
tomography) scans to create “movies” of the dopamine
response during smoking to demonstrate for the first
time that smoking-induced dopamine activation occurs
in a different brain region and much faster in
nicotine-dependent men than women.
In practical terms, identifying and understanding
the neurobiological underpinnings of the sex
differences in smoking behavior, by identifying
unique “dopamine signatures” of nicotine-dependence
in men and women could provide paths for developing
and testing gender-sensitive medications and other
approaches for quitting smoking.
“By way of analogy, think of an EKG,” explained Evan
D. Morris, associate professor of diagnostic
radiology, biomedical engineering, and psychiatry,
researcher at the Yale Cancer Center, and the senior
author on the study. “It shows you a pattern of
electrical activity in the heart over the whole
cardiac cycle. You can’t identify tachycardia from a
single moment in the EKG. Similarly, our dopamine
movies show patterns of dopamine activation in the
brain over time. This was not possible previously.
We hope to find patterns that indicate addiction and
patterns that indicate effectiveness of treatment
for addiction.”
In the new study, 16 nicotine-dependent smokers —
eight men and eight women — underwent PET brain
scanning during smoking sessions. A novel method of
analyzing the results allowed the research team to
create dynamic images, “dopamine activation movies,”
to visualize rapidly changing levels of the
neurotransmitter. Brief bursts of dopamine activity
— such as one gets from smoking a cigarette — were
previously unmeasurable with PET imaging.
The Yale team found that dopamine release in
nicotine-dependent men during smoking was consistent
and rapid in the right ventral striatum, a region of
the brain central to the reinforcement effect of
drugs such as nicotine. A similarly rapid dopamine
response was found only in women in a part of the
dorsal striatum, a brain region that also happens to
be critical for habit formation.
These findings are consistent with the established
notion that men smoke for the reinforcing drug
effect of nicotine and that they are sensitive to
the nicotine level, while women tend to smoke for
other reasons, such as to alleviate negative mood
and stress or from habit. However, the
neurobiological bases for these sex differences have
eluded researchers, making it difficult to design
gender-specific smoking cessation treatments.
“We might expect nicotine replacement to change the
dopamine movie of a typical male smoking but not a
female,” said Kelly Cosgrove, associate professor of
psychiatry, diagnostic radiology, and neurobiology,
and the lead author. “If our hypothesis pans out,
then dopamine movies may help explain why
nicotine-replacement therapies, such as nicotine
patches, appear to be more effective for male
smokers than for women.”
The study was supported by the National Institute on
Drug Abuse and the National Institutes of Health
Office of Research on Women’s Health, through the
Yale Translational Center to Develop
Gender-Sensitive Treatment for Tobacco Dependence.
Other authors from Yale on the study were Shuo Wang,
Su-Jin Kim, Erin McGovern, Nabeel Nabulsi, Hong Gao,
David Labaree, Hemant D. Tagare, and Jenna M.
Sullivan.
See also
Quitting smoking? Time it with your period
(2015-01-05)
For more information
Sex Differences in the Brain's Dopamine Signature of
Cigarette Smoking
Yale
University
MDN |